Chalk Talks

Location:

Natio Laboratory, Room 205, 12 Oxford Street

Abstract: The carbon isotopic composition of algal organic matter preserved in marine sediments provides a window into the evolution of the global carbon cycle through geologic time, including variations in atmospheric CO2 levels. Traditional models for interpreting marine isotope records assume that these archives largely reflect kinetic isotopic discrimination by the carbon-fixing enzyme RubisCO. However, recent measurements in our laboratory and in the literature appear to contradict this assumption, indicating that significant questions remain regarding the...

Location:

Location:

Natio Laboratory, Room 205, 12 Oxford Street

The building blocks of life as we know it, including amino acids, nucleobases, and sugars, were synthesized early in the history of the solar system in space, in processes likely common throughout the universe. After delivery to habitable worlds, such building blocks may have biased independent origins of life, if they occurred, towards similar solutions. For example, nucleic acids or their cousins may serve as a common physical basis for heritability and evolution. Nucleic acid-based informational polymers (IPs) are even more likely for any life that may exist or may have once existed on...

Location:

Natio Laboratory, Room 205, 12 Oxford Street

Abstract

The recent Kepler mission discovered thousands of new worlds beyond our Solar System, hundreds of which may be terrestrial planets of similar size to our Earth. The mass of a planet is arguably its most fundamental physical parameter; it dictates its internal composition and structure, and its ability to have an atmosphere, an essential component for a potentially life-hosting planet. In an era of large telescopes and high-precision instruments, the ultimate challenge to determining the masses of small, rocky exoplanets lies not in our technological...

Location:

Natio Laboratory, Room 205, 12 Oxford Street

This Chalk Talk will be a panel discussion of Origins Graduate Consortium student members, moderated by Dimitar Sasselov, as they share their assessment of the Consortium’s first field trip, a five-day trip to Pasadena, California in June 2016.Visits to the Jet Propulsion Laboratory, Mount Wilson, the Giant Magellan Telescope headquarters, and CalTech focused on astrobiology and exoplanet searches and characterization.

Location:

Naito Laboratory, Room 205, 12 Oxford St, Cambridge

Abstract - Our living world is the result of a complex history spanning billions of years. Scientists have access to artifacts of this history, namely the fossil record and the genomes of many different living organisms. But there are surprisingly limited means with which to infer critical evolutionary elements in the deep past that resulted in modern biota. It is particularly difficult to reconcile (sometimes cryptic) fossil morphology on one hand, and genetic composition and diversification over time on the other, when so little about the behavior of ancestral organisms can be...

Location:

Naito Laboratory, Room 205, 12 Oxford St, Cambridge

Abstract -

Information processing is fundamental to life: metabolism, replication, evolution, etc all rely on it. Extant living systems carry out information processing chemically, using biochemistry. Chemistry-based computation is key to the information processing taking place in life. The most powerful, and yet simple, known construct in computation is the Turing machine. It consists of a finite state machine capable of giving unique responses to inputs from an infinite tape on which it can also write and erase. A Turing machine emulates a mathematician carrying...

Location:

Naito Laboratory, Room 205, 12 Oxford St, Cambridge

Abstract- I will attempt to give an overview of some basic principles involved in nonenzymatic (RNA) replication using the language of statistical mechanics. I will give a mathematical definition of fidelity in terms of thermodynamic and kinetic constants, and try to demonstrate the connection between entropy and the transmission of information in this context. My main goal is to try to convey a general idea of nonenzymatic replication using the language of physics, rather than specific chemical structures, in an effort to gives those non-chemists/biologists in the...

Location:

Naito Laboratory, Room 205, 12 Oxford Street, Cambridge

Abstract:

The nearby low-mass stars are the best candidate hosts for searching for transiting exoplanets to enable future characterization of their atmospheres. Unfortunately, our understanding of exoplanets is most often limited by our ability to characterize the host star. In this talk, I will focus on this stellar characterization problem, and how the MEarth transit survey has enabled us to better understand these stars. MEarth consists of 2 arrays of 8 telescopes each, one located at Mt. Hopkins, Arizona, and the other at Cerro Tololo, Chile. First, I used data from the...

Location:

Naito Laboratory, Room 205, 12 Oxford St, Cambridge

Abstract:From PREM (Dziewonski & Anderson 1981), I deduce a simple analytical model for rocky planets. Tested with PREM-extrapolated numerical models (Zeng, Sasselov, Jacobsen 2015), this model can be applied to any two-layer (iron-silicate) rocky exoplanets with CMF (core mass fraction) range 0.2∼0.35 and mass range of 0.1~20 M⊕. This analytical model yields several handy and powerful formulae for the interior of such a planet. They can provide physical insights into the planet structure.

Location:

Naito Laboratory, Room 205, 12 Oxford St, Cambridge

Abstract: I will describe recent work on the development of a sensitive magnetic-field microscope with sub-micrometer spatial resolution. This instrument employs a layer of nitrogen-vacancy (NV) color centers at the surface of a diamond chip to enable imaging of magnetic fields from nearby samples. Together with collaborators in the MIT department of Earth, Atmospheric and Planetary Sciences, we have used the NV-diamond microscope to study distributions of magnetic minerals in a variety of terrestrial and meteoric rocks. The combination of spatial resolution and magnetic sensitivity of our...

Location:

Naito Laboratory, Room 205, 12 Oxford St, Cambridge

Abstract: Organic molecules preserved in sedimentary rocks are generally regarded as robust recorders of the biology and chemistry of ancient environments. Here I will outline our recent efforts to extract, quantify, and measure the isotopic composition of compounds derived from chlorophyll molecules in organic-rich rocks. Their nitrogen stable isotope compositions are of particular interest because they record fingerprints of ancient ocean biogeochemistry that are not found in modern seas. Hypotheses for these observations include enhanced ammonium recycling and redox control on the...

Location:

Naito Laboratory, Room 205, 12 Oxford St

Abstract - My group members and myself are interested in the energy cycles of prebiotic molecular networks and metabolism. To be able to explore such networks, we have developed methods that combine heuristic reaction rules with quantum chemical calculations to be able to explore quickly the highly-dimensional potential energy surfaces associated with these reactions. We have explored the formose reaction and compared its network properties to those of metabolic networks. We also have explored the non-enzymatic reverse tricarboxilic acid cycle to determine its uniqueness amongst other...

Location:

Naito Laboratory, Room 205, 12 Oxford Street

Life and living systems (LS) constitute the most complex class of natural phenomena that we know on Earth and, at least for now, in the Universe. Their functioning involves thousands of biochemical reactions and processes, all working at many different temporal and spatial scales. When it comes to understand Life and its properties, the traditional approach is to start from details and work from there to a full understanding of the complete system, i.e. a bottom-up process. In this talk we will discuss a completely different, but complementary, (top-down) approach. Starting from basic...